POLYGON mode problem

hi!. i just a begginner in OPENGL. im studing computer Engeneering at Argentina.i`ve a problem drawing polygons. is not a code problem!. i see diferents things in my computer. when i draw a square with gl_polygon i see two triangles “joined”, when i try the same program on another PC y see the correct square without the “midium line”. i contact HW technical support of my video card, and the said “it’s a application problem”.my video card is reconogized as Sis 740, its onboard on a old PCHIPS M810DLU MOtherBoard. thanks and excuse me for my english.

I had a similar problem with visible lines between triangles, because I enabled GL_POLYGON_SMOOTH.
If you don’t have GL_POLYGON_SMOOTH enabled I really don’t know what is causing this problem.

Most of graphics cards (probably all) can’t draw other polygons than triangles so if you draw a rectangle it will always be made of two joined triangles.
The thing is that you shouldn’t see edge between these triangles so it seems like a driver problem.
Check your driver. Also check if you have some antialiasing or other things (like POLYGON_SMOOTH mentioned above) enabled. Actually, neither antialiasing nor POLYGON_SMOOTH should cause this kind of problem.
If you see a gap (empty pixels) between triangles drawn using one GL_POLYGON then technical support should not so easily assume it’s an application problem.

thanks!!! it was a driver problem. but windows detect the “Correct” dreiver as a incorrectr driver. anyway your comments were very helpfull.THANKS!!!:slight_smile: